Heat exchanger with improved liquid/gas mixing device

ABSTRACT

The invention concerns a heat exchanger comprising several plates arranged parallel to one another and to a longitudinal direction so as to define a first series of passages for channeling at least one first fluid and a second series of passages for channeling at least one second fluid which is to be brought into a heat-exchange relationship with at least said first fluid, a mixer device being arranged in said at least one passage of the first series and comprising at least one first channel for the flow of a first phase of the fluid in the longitudinal direction, at least one second channel for the flow of a second phase of the fluid, and a plurality of orifices fluidically connecting the first channel to the second channel, said orifices occupying successive positions in the longitudinal direction. According to the invention, the distances between two successive positions, measured parallel to the longitudinal direction, are variable.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a § 371 of International PCT ApplicationPCT/FR2019/050642, filed Mar. 21, 2019, which claims the benefit ofFR1852469, filed Mar. 22, 2018, both of which are herein incorporated byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates to a heat exchanger comprising series ofpassages for each of the fluids to be placed in a heat-exchangerelationship, the exchanger comprising at least one mixer device fordistributing at least one two-phase liquid/gas mixture into one of theseries of passages.

In particular, the present invention may apply to a heat exchanger whichvaporizes at least one flow of liquid-gas mixture, particularly a flowof multi-constituent mixture, for example a mixture of hydrocarbons,through exchange of heat with at least one other fluid, for examplenatural gas.

BACKGROUND OF THE INVENTION

The technology commonly used for an exchanger is that of aluminum brazedplate and fin exchangers, which make it possible to obtain devices thatare very compact and afford a large heat-exchange surface area.

These exchangers comprise plates between which are insertedheat-exchange corrugations, formed of a succession of fins orcorrugation legs, thus constituting a stack of vaporization passages andof condensation passages, the former intended to vaporize refrigerantliquid and the latter intended to condense a calorigenic gas. Theexchanges of heat between the fluids may take place with or withoutphase change.

In order to ensure correct operation of an exchanger employing aliquid-gas mixture, the proportion of liquid phase and of gas phaseneeds to be the same in all of the passages and needs to be uniformwithin one and the same passage.

The dimensions of the exchanger are calculated on the assumption of auniform distribution of the phases, and therefore of a singletemperature at the end of vaporization of the liquid phase, equal to thedew point of the mixture.

In the case of a multi-constituent mixture, the temperature at the endof vaporization is going to depend on the proportion of liquid phase andof gas phase in the passages.

In the event of an unequal distribution of the two phases, thetemperature profile of the first fluid is then going to vary frompassage to passage, or even vary within one and the same passage.Because of this non-uniform distribution, there is then the possibilitythat the fluid(s) in a heat-exchange relationship with the two-phasemixture may have an exchanger outlet temperature that is higher thanintended, and this consequently degrades the performance of the heatexchanger.

One solution for distributing the liquid and gas phases of the mixtureas uniformly as possible is to introduce them into the exchangerseparately, then mix them together only once they are inside theexchanger.

Document FR-A-2563620 describes such an exchanger in which a grooved baris inserted into the series of passages which is intended to channel thetwo-phase mixture. This mixer device comprises separate channels for aliquid phase and for a gas phase, and an outlet for distributing theliquid-gas mixture to the heat-exchange zone.

A problem which arises with this type of mixer device concerns thedistribution of the liquid-gas mixture in the width of the passagecontaining the mixer device. In order to mix the two phases, the mixerdevice generally comprises a first channel for the flow of one phase.This channel is equipped with a series of orifices arranged along thechannel, each orifice being in fluidic communication with the secondchannel for the flow of the other phase. When the inlet to the firstchannel is supplied with fluid, the flow rate of the fluid will tend todiminish as the fluid flows along the channel. This is because the flowof fluid reduces as the orifices are supplied.

Now, the orifices are generally machined perpendicularly to thedirection of flow of the fluid, and are therefore less well suppliedwhen the fluid speed is higher. The orifices arranged on the channelinlet side therefore have a tendency to be under-supplied, whereas theorifices situated on the bottom of the channel are over-supplied. Theresult is an uneven introduction of the respective phase into thechannel for the other phase, and hence an uneven distribution of theliquid-gas mixture in the width of the exchanger passage.

In order to minimize this phenomenon, one solution is to supply thechannel concerned via two opposite inlets of the channel. However, thisresults in a complication of the exchanger, and the problem of unevendistribution remains at least in the central part of the channel.

Increasing the number of channels is also not an ideal solution in viewof the mechanical strength and brazing of the device.

Another known solution is to arrange orifices of cylindrical form withdifferent diameters along the channel. However, this solution may proveinsufficient for certain processes.

SUMMARY OF THE INVENTION

It is an object of certain embodiments of the present invention to fullyor partially solve the above-mentioned problems, notably by proposing aheat exchanger in which the distribution of the liquid and gas phases ofa mixture is as uniform as possible, and to do so without excessivelyadding to the complexity of the structure of the exchanger, orincreasing the size thereof.

The solution according to the invention is therefore a heat exchangercomprising several plates arranged parallel to one another and to alongitudinal direction so as to define a plurality of passages forchanneling at least one fluid which is to be brought into aheat-exchange relationship with at least one other fluid, a mixer devicebeing arranged in at least one passage and comprising:

-   -   at least one first channel for the flow of a first phase of the        fluid parallel to the longitudinal direction,    -   at least one second channel for the flow of a second phase of        the fluid, and    -   a plurality of orifices fluidically connecting the first channel        to the second channel, said orifices occupying successive        positions in the longitudinal direction,    -   wherein the distances between the successive positions, measured        parallel to the longitudinal direction, are variable.

Depending on the case, the exchanger of the invention may comprise oneor more of the following technical features:

-   -   the distances between the successive positions vary        monotonically or near-monotonically in the longitudinal        direction.    -   the mixer device exhibits, in the longitudinal direction, an        increase in the distances between two successive positions.    -   the mixer device exhibits, in the longitudinal direction, a        decrease in the distances between two successive positions.    -   the mixer device is divided, in the longitudinal direction, into        at least a first portion and a second portion, the first portion        exhibiting, in the longitudinal direction, an increase in the        distances between two successive positions, and the second        portion exhibiting, in the longitudinal direction, a decrease in        the distances between two successive positions.    -   the mixer device is configured for a separate introduction of        the first phase and of the second phase into the at least one        first channel and into the at least one second channel,        respectively, the first channel comprising a first inlet        designed to supply said first channel with the first phase of        the first fluid and a second inlet, separate from the first        inlet, designed to supply said at least one second channel with        the second phase of the first fluid.    -   the first channel and/or the second channel are rectilinear in        shape.    -   the mixer device comprises a first inlet and an additional first        inlet which are designed to supply said at least one first        channel with the first phase of the fluid, the first portion        being situated on the side of the first inlet and the second        portion being situated on the side of the additional first        inlet.    -   the mixer device comprises several first channels and several        second channels, each first channel comprising at least one        orifice fluidically connecting said first channel to a given        second channel.    -   the mixer device comprises several first channels succeeding one        another in a lateral direction orthogonal to the longitudinal        direction.    -   the second channel extends in a lateral direction orthogonal to        the longitudinal direction.

Furthermore, the invention relates to a method for distributing atwo-phase liquid/gas mixture in an exchanger according to the invention,said method comprising the following steps:

-   -   i) arranging a mixer device in at least one passage of the        exchanger,    -   ii) supplying said first channel of the mixer device with the        first phase of the first fluid,    -   iii) supplying said second channel of the mixer device with the        second phase (62) of the first fluid (F1), which is distinct        from the first phase (61),    -   iv) establishing fluidic communication between the first channel        and the second channel via the orifices so that a mixing between        the first phase and the second phase takes place within the        mixer device, and    -   distributing a mixture of the first phase and of the second        phase at the outlet of the mixer device.

According to another aspect, the invention relates to a method foradjusting the positions of the orifices of a mixer device which isarranged in an exchanger according to the invention, said methodcomprising the following steps:

-   -   a) positioning the orifices in such a way that their successive        positions are separated by predetermined distances,    -   b) supplying the first channel with the first phase of the fluid        such that the first phase of the fluid flows in the longitudinal        direction,    -   c) determining the mass flow rates of the first phase flowing        through each orifice,    -   d) for each orifice, repositioning the next orifice so that it        is separated from the orifice by a modified distance equal to        the mean of the predetermined distances multiplied by a        correction factor, said correction factor being determined on        the basis of the mass flow rate flowing through the orifice.    -   the correction factor is a function of the ratio between the        mass flow rate flowing through the orifice and the mass flow        rate averaged over all the orifices.    -   said function is a polynomial function of the ratio between the        mass flow rate flowing through the orifice and the mass flow        rate averaged over all the orifices, preferably an affine        function of said ratio.    -   the method further comprises a step e) of defining the distances        modified in step d) as predetermined distances, steps c) to d)        being reiterated at least once, preferably between 1 and 5        times, more preferably at most twice.    -   the mixer device comprises several first channels, the method        comprising, prior to step a), at least one step of selecting a        subset of orifices which are arranged in one and the same first        channel, steps a) to e) being applied to said subset.

The present invention may apply to a heat exchanger which vaporizes atleast one flow of liquid-gas mixture, particularly a flow ofmulti-constituent mixture, for example a mixture of hydrocarbons,through exchange of heat with at least one other fluid, for examplenatural gas.

The expression “natural gas” relates to any composition containinghydrocarbons, including at least methane. This comprises a “crude”composition (prior to any treatment or scrubbing) and also anycomposition which has been partially, substantially or completelytreated for the reduction and/or removal of one or more compounds,including, but without being limited thereto, sulfur, carbon dioxide,water, mercury and certain heavy and aromatic hydrocarbons.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features, advantages and possible applications of the inventionare apparent from the following description of working and numericalexamples and from the drawings. All described and/or depicted featureson their own or in any desired combination form the subject matter ofthe invention, irrespective of the way in which they are combined in theclaims or the way in which said claims refer back to one another.

The present invention will now be better understood by virtue of thefollowing description, given solely by way of nonlimiting example andmade with reference to the attached drawings, among which:

FIG. 1 is a schematic view, in a plane of section parallel to the platesof a heat exchanger, of part of a passage of an exchanger supplied witha two-phase liquid-gas mixture, according to one embodiment of theinvention;

FIG. 2 is a schematic view in cross section, in a plane perpendicular tothat of FIG. 1, of the mixer device of FIG. 1;

FIG. 3 is a three-dimensional schematic view illustrating a mixer deviceaccording to various embodiments of the invention;

FIG. 4 is a three-dimensional schematic view illustrating a mixer deviceaccording to various embodiments of the invention;

FIG. 5 presents results of simulations carried out with a mixer deviceaccording to the invention and with a mixer device outside of theinvention;

FIG. 6 presents results of simulations carried out with a mixer deviceaccording to the invention and with a mixer device outside of theinvention;

FIG. 7 presents results of simulations carried out with a mixer deviceaccording to the invention and with a mixer device outside of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a heat exchanger 1 comprising a stack of plates 2(not shown) which extend in two dimensions parallel to a plane definedby a longitudinal direction z and a lateral direction y. The plates 2are arranged parallel to and above one another with a spacing, and thusform a plurality of passages for fluids in an indirect heat-exchangerelationship via said plates.

For preference, each passage has a flat and parallelepipedal shape. Theseparation between two successive plates is small in comparison with thelength, measured in the lateral direction y, and the width, measured inthe longitudinal direction z, of each passage.

The exchanger 1 may comprise a number of plates in excess of 20, or evenin excess of 100, between them defining a first series of passages 10for channeling at least one first fluid F1, and a second series ofpassages 20 (not visible in FIG. 1) for channeling at least one secondfluid F2, the flow of said fluids being overall in the direction y. Thepassages 10 of the first series may be arranged, wholly or partially, toalternate with, or to be adjacent to, all or some of the passages 20 ofthe second series.

In a way known per se, the exchanger 1 comprises distribution anddischarge means 40, 52, 45, 54, 55 configured to distribute the variousfluids selectively into the passages 10, 20 and to discharge said fluidsfrom said passages 10, 20.

The sealing of the passages 10, 20 along the edges of the plates 2 isgenerally afforded by lateral and longitudinal sealing strips 4 attachedto the plates 2. The lateral sealing strips 4 do not completely blockthe passages 10, 20 but advantageously leave fluid inlet and outletopenings situated in the diagonally opposite corners of the passages.

The openings of the passages 10 of the first series are arranged incoincidence one above the other, whereas the openings of the passages 20of the second series are arranged in the opposite corners. The openingsplaced one above the other are respectively united with one another inmanifolds 40, 45, 50, 55 of semi-tubular shape via which the fluids aredistributed and discharged.

In the depiction of FIG. 1, the semi-tubular manifolds 50, 45 are usedto introduce the fluids into the exchanger 1, and the semi-tubularmanifolds 40, 55 are used to discharge these fluids from the exchanger1.

In this variant embodiment, the manifold supplying one of the fluids andthe manifold discharging the other fluid are situated at one and thesame end of the exchanger, the fluids F1, F2 thus flowingcounter-currently through the exchanger 1.

According to another variant embodiment, the first and second fluids mayequally circulate co-currently, the means supplying one of the fluidsand the means discharging the other fluid then being situated atopposite ends of the exchanger 1.

For preference, the direction y is oriented vertically when theexchanger 1 is in operation. The first fluid F1 flows generallyvertically and in the upward sense of that direction. Other directionsand senses for the flow of the fluids F1, F2 are of course conceivable,without departing from the scope of the present invention.

It should be noted that, in the context of the invention, one or morefirst fluids F1 and one or more second fluids F2 of different naturesmay flow within the passages 10, 20 of the first and second series ofone and the same exchanger.

As a preference, the first fluid F1 is a refrigerant fluid and thesecond fluid F2 is a calorigenic fluid.

The distribution and discharge means of the exchanger advantageouslycomprise distribution corrugations 51, 54, arranged between twosuccessive plates 2 in the form of corrugated sheets, which extend fromthe inlet and outlet openings. The distribution corrugations 51, 54ensure the uniform distribution and recovery of the fluids across theentire width of the passages 10, 20.

Furthermore, the passages 10, 20 advantageously comprise heat-exchangestructures arranged between the plates 2. The purpose of thesestructures is to increase the heat-exchange surface area of theexchanger and to increase the coefficient of exchange between the fluidsby making the flows more turbulent. Specifically, the heat-exchangestructures are in contact with the fluids circulating in the passagesand transfer thermal flux by conduction to the adjacent plates 2, towhich they may be attached by brazing, thereby increasing the mechanicalstrength of the exchanger.

The heat-exchange structures also act as spacers between the plates 2,notably while the exchanger is being assembled by brazing, and in orderto avoid any deformation of the plates during use of pressurized fluids.They also provide guidance for the flows of fluid in the passages of theexchanger.

For preference, these structures comprise heat-exchange corrugations 11which advantageously extend across the width and the length of thepassages 10, 20, parallel to the plates 2, in the prolongation of thedistribution corrugations along the length of the passages 10, 20. Thepassages 10, 20 of the exchanger thus exhibit a main part of theirlength, constituting the heat-exchange part proper, which is coveredwith a heat-exchange structure, said main part being flanked bydistribution parts covered with the distribution corrugations 51, 54.

FIG. 1 illustrates a passage 10 of the first series 1, configured todistribute a first fluid F1 in the form of a two-phase mixture alsoreferred to as a biphasic mixture. The first fluid F1 is separated in aseparator device 6 into a first phase 61 and a second phase 62 which areintroduced separately into the exchanger 1 via a first manifold 30 and asecond manifold 50 which are distinct from one another. The first andsecond phases 61, 62 are then mixed together by means of a mixer device3 arranged in the passage 10. Advantageously, several passages 10, oreven all of the passages 10 of the first series, comprise a mixer device3. In the case illustrated in FIG. 1, the first phase 61 is liquid andthe second phase 62 is gaseous.

FIG. 2 is a schematic view in cross section, in a plane perpendicular tothat of FIG. 1, of a mixer device 3 advantageously comprising a bar orrod housed in a passage 10.

The mixer device 3 preferably extends in the section of the passage 10over almost all of the, or even the entire, height of the passage 10,such that the mixer device is in contact with each plate 2 that formsthe passage 10.

The mixer device 3 is advantageously fixed to the plates 2 by brazing.

The mixer device 3 is advantageously of generally parallelepipedalshape.

As a preference, the mixer device 3 is a monolithic component, namelyformed as a block or as a single piece. The mixer device 3 may have,parallel to the lateral direction y, a first dimension of between 20 and200 mm and, parallel to the longitudinal direction z, a second dimensionof between 100 and 1400 mm.

As a preference, the first channel 31 extends over the entirety of thesecond dimension and/or the second channel extends over the entirety ofthe first dimension.

The mixer device 3 comprises at least a first channel 31 for the flow ofthe first phase 61 parallel to the longitudinal direction z, and atleast a second channel 32 for the flow of the second phase 62. Saidfirst channel 31 extends parallel to the longitudinal direction z. As apreference, the first channel 31 and/or the second channel arerectilinear in shape. As a preference, the second channel 32 extendsparallel to the lateral direction y which is orthogonal to thelongitudinal direction z and parallel to the plates 2.

A plurality of orifices 34 _(i), 34 _(i+1), . . . are distributed overthe mixer device 3 so as to fluidically connect at least a first channel31 with at least a second channel 32 designed for the flow of the secondphase 62. The mixer device 3 is configured so that when the first phase61 is flowing along the first channel 31 and the second phase 62 isflowing along the second channel 32, a two-phase liquid/gas mixture F1is distributed at outlet from the mixer device 3.

As a preference, the mixer device 3 comprises at least one first inlet311 in fluidic communication with the first manifold 30, and a secondinlet 321, separated from the first inlet 311, in fluidic communicationwith the second manifold 50. The first manifold 30 is fluidicallyconnected to a source of first phase 61, and the second manifold 50 isfluidically connected to another source of second phase 62. Said atleast one first inlet 311 and said at least one second inlet 321 areplaced in fluidic communication via the orifices 34 _(i), 34 _(i+1), . ..

As a preference, the mixer device 3 comprises a mixing volume situatedin the second channel 32, downstream of the orifice 34 i, when followingthe direction of flow of the first phase 61 through the orifice 34 i.The two-phase liquid/gas mixture is distributed via a second outlet 322of the second channel 32.

The first and second channels 31, 32 advantageously take the form oflongitudinal recesses formed in the mixer device 3.

The orifices 34 are advantageously bores 34 made in the material of thedevice 3 and extending between the first channel 31 and the secondchannel 32, preferably in the vertical direction x. As a preference, theorifices 34 exhibit cylindrical symmetry.

As a preference, said at least one first channel 31 comprises a bottomwall 3 c and said at least one second channel comprises a top wall 3 dwhich faces the bottom wall 3 c, the orifices 34 being pierced in thebottom wall of the first channel 31 and opening into the top wall of thesecond channel 32.

FIG. 3 is a three-dimensional view of the mixer device 3 of FIG. 2, FIG.2 schematically showing the device 3 in a plane of section orthogonal tothe longitudinal direction z and passing through the orifice 34 _(i).

As can be seen in FIG. 3, the orifices 34 _(i), 34 _(i+1), . . . occupysuccessive positions z_(i), z_(i+1), . . . in the longitudinal directionz. Each orifice 34 _(i) is separated from the next orifice 34 _(i+1) bya distance denoted d_(i) which is measured parallel to the longitudinaldirection z.

In the devices according to the prior art, the orifices occupysuccessive positions z_(i), z_(i+1), . . . that are situated at equaldistances from one another. Now, the first phase 61 flows along thefirst channel 31 at different speeds along the length of thelongitudinal direction z, and the flow of first phase 61 flowing througheach orifice varies according to the speed of flow of the first phase 61at the position z_(i) of the orifice concerned.

In order to solve this problem, what is proposed is a mixer device 3 inwhich the distances between two successive positions z_(i), z_(i+1), . .. are variable. In other words, the distances between the successivepositions z_(i), z_(i+1), . . . are not all identical. At least one pairof successive orifices exhibits a distance between two successivepositions that differs from that of another pair of successive orifices.

By varying the distances between orifices in the longitudinal directionz, it is possible to compensate for nonuniformities of flow rates perunit length in the longitudinal direction z or, to put it another way,per unit width of exchanger passage, distributed by the orifices 34 byadapting the distribution of the orifices 34 across the width of themixer device 3. “Flow rate per unit length” typically means a flowdistributed by an orifice, divided by the distance between this orificeand the next one. For example, greater distances may be left betweenorifices which have a tendency to be oversupplied with a flow of fluidin the first phase 61, and this will have the effect of locally reducingthe flow rate per unit width distributed by the orifices. In fact, theaim is not to make the flow of fluid passing through each of theorifices 34 _(i), 34 _(i+1), . . . uniform by adjusting theconfiguration of the orifices 34 or of the first channel 31, but ratherto adapt the distribution of the points via which fluid is distributedby the orifices 34 in such a way as to render the flow rate of firstphase 61 per unit length uniform in the longitudinal direction z.

This then results in a more uniform distribution of the liquid-gasmixture across the width of the passage 10. This solution offers theadvantages of being simple to implement, of not altering the size of theexchanger, and of not making its structure more complex.

According to one embodiment, the distances between the successivepositions z_(i), z_(i+1), . . . vary monotonically or near-monotonicallyin the longitudinal direction z. In other words, the direction ofvariation of the successive positions is constant or generally constantalong the length of the longitudinal direction z.

According to one embodiment, the mixer device 3 exhibits, in thelongitudinal direction z, an increase in the distances between twosuccessive positions z_(i), z_(i+1), . . . . Such a configuration isimplemented when the mixer device 3 is supplied with first phase 61 viaa first inlet 311, the first phase flowing in the longitudinal directionz, as illustrated in the example of FIG. 3. The orifices situated on theside of the inlet 311 have a tendency to be undersupplied in comparisonwith the orifices situated further downstream, when following thedirection of flow of the first phase 61.

According to an embodiment variant (not illustrated), the mixer device 3exhibits, in the longitudinal direction z, a reduction in the distancesbetween two successive positions z_(i), z_(i+1), . . . Such aconfiguration is implemented when the mixer device 3 is supplied withfirst phase 61 via an additional first inlet 312 arranged in such a waythat the first phase 61 flows parallel but in the opposite sense to thelongitudinal direction z.

FIG. 4 illustrates another embodiment of the invention which isparticularly advantageous when the mixer device 3 has two inlets forsupply of the first phase 61. More specifically, the mixer device 3 issupplied with first phase 61 via a first inlet 311 and an additionalfirst inlet 312. The mixer device 3 is divided, in the longitudinaldirection z, into at least a first portion 301 and a second portion 302,the first portion 301 exhibiting, in the longitudinal direction z, anincrease in the distances between two successive positions z_(i),z_(i+1), . . . , and the second portion 302 exhibiting, in thelongitudinal direction z, a decrease in the distances between twosuccessive positions z_(i), z_(i+1), . . .

This embodiment allows the flow of first phase 61 distributed downstreamof the orifices 34 to be made even more uniform along the length of thelongitudinal direction z.

As a preference, the first inlet and the additional first inlet 311, 312are arranged at two opposite ends of the mixer device 3. A first flow offirst phase 61 is distributed by the first inlet 311 and flows in thedirection of flow z, and a second flow of first phase 61 is distributedby the additional first inlet 312 and flows parallel, but in theopposite sense, to the longitudinal direction z.

Advantageously, the first portion 301 is situated on the side of thefirst inlet 311 and the second portion 302 is situated on the side ofthe additional first inlet 312.

As a preference, the first and second portions 301, 302 are arrangedsymmetrically relative to the center of the mixer device 3. However,said portions could be arranged in different numbers and exhibitdifferent amplitudes of variations in distances between successiveorifices on either side of the center of the mixer device 3.

Advantageously, a mixer device 3 according to the invention may beconfigured by adjusting the position of the orifices 34 according to thesteps described hereinafter. Note that all or some of these steps may beperformed by numerical simulation, for example using Computational FluidDynamics (CFD), or by correlating pressure drops along the first channel31 and orifices 34, or by actual measurements, etc.

An initial state of the mixer device 3 is defined in which the orifices34 _(i), 34 _(i+1), . . . are arranged in successive positions z_(i),z_(i+1), . . . that are separated by predetermined distances d_(i),d_(i+1), . . . As a preference, in the initial state, the predetermineddistances di, d_(i+1), . . . are identical.

The first channel 31 is supplied in such a way that the first phase 61flows in the longitudinal direction z. The mass flow rates Q_(i),Q_(i+1), . . . of the first phase 61 flowing through each orifice 34_(i), 34 _(i+1), . . . of the mixer device 3 are determined and theorifices are repositioned in such a way that, for each orifice 34 _(i),the next orifice 34 _(i+1) is situated away from the previous orifice 34_(i) by a modified distance d_(i) that is expressed:

d _(i) =F _(i) ×d _(m)

where d_(m) is the mean of the predetermined distances d_(i), d_(i+1), .. . and F_(i) is a correction factor determined for each orifice asbeing a function of the flow rate Q_(i) flowing through the orifice 34_(i).

It should be noted that, for preference, in the initial state, the meandistance between orifices corresponds to the identical distanceseparating all the orifices 34 _(i), 34 _(i+1), . . . .

Advantageously, the correction factor F_(i) is a function of the ratioQ_(i)/Q_(m) between the mass flow rate Q_(i) flowing through the orifice34 _(i) and the mass flow rate Q_(m) averaged over all the orifices.

As a preference, this function is a polynomial function of the ratioQ_(i)/Q_(m), more preferably an affine function of the ratioQ_(i)/Q_(m), expressed:

$F_{i} = {{A \times \frac{Q_{i}}{Q_{m}}} + B}$

where Q_(i) is the mass flow rate flowing through the orifice 34 _(i),Q_(m) is the mass flow rate averaged over all the orifices, A and B arepredetermined constants dependent on the characteristics of the mixerdevice 3. According to one particular embodiment, A=1 and/or B=0.

It being emphasized that the adjustment method described can be appliedwhatever the configuration of supply with first phase 61 of the firstchannel 31 since it is in the determination of the flow rates Q_(i),Q_(i+1), . . . that the configuration of supply of the first channel 31is involved.

According to the exchange method considered and its sensitivity to theuneven distribution of the phases of the first fluid F1, one single stepof repositioning the orifices 34 _(i), 34 _(i+1), . . . may suffice toeven out the distribution of the first phase across the width of themixer device 3.

Optionally, the step of repositioning the orifices 34 _(i), 34 _(i+1), .. . may be reiterated at least once, preferably between 1 and 5 times,more preferably twice at most. The adjustment method then comprises astep of defining the distances d_(i), d_(i+1), . . . modified previouslyas predetermined distances. The new mass flow rates Q_(i), Q_(i+1), . .. of the first phase 61 flowing through each repositioned orifice 34_(i), 34 _(i+1), . . . are determined. The mean distance d_(m) betweenthe orifices and the mean flow rate Q_(m) flowing through the orificesare calculated and new modified distances d_(i), d_(i+1), . . . aredetermined, using the expressions given hereinabove.

In the case of a mixer device 3 having several first channels 31, theadjustment method may be performed generally on all of the firstchannels 31 together, by considering the distances d_(i), d_(i+1), . . .between two successive orifices, whether these orifices be arranged inone and the same first channel 31 or in different first channels 31.

Alternatively, the method may be performed by considering each firstchannel 31 individually. In order to do that, the method may optionallycomprise, prior to step a), at least one step of selecting a subset oforifices 34 _(i), 34 _(i+1), . . . which are arranged in one and thesame first channel 31, steps a) to e) being executed for said subset. Atleast one other subset of orifices 34 _(i), 34 _(i+1), . . . arranged inanother first channel 31 may then be selected and steps a) to e)executed for this other subset.

In order to demonstrate the effectiveness of the invention, CFDsimulations have been run with a mixer device 3 as illustrated in FIG.4. A series of three first channels 31 was supplied via two opposedinlets 301, 302 with a first phase 61 in the liquid state. The orifices34 were cylindrical in shape and extended in the vertical direction x.In order to simplify the simulations, only the first phase 61 was takeninto consideration, the gaseous second phase 62 being considered to havea negligible influence on the distribution of the liquid first phase 61through each orifice 34.

The results of these simulations are given in FIGS. 5 and 6, with acomparison between a mixer device 3 having equidistant orifices (outsideof the invention) and a mixer device 3 comprising a first portion 301exhibiting, in the longitudinal direction z, an increase in thedistances between two successive positions , and the second portion 302exhibiting, in the longitudinal direction z, a decrease in the distancesbetween two successive positions z_(i), z_(i+1), . . . (of theinvention). FIG. 5 shows the evolution of the distances between orificesin the longitudinal direction z. In the initial state, the orifices areequidistant (outside of the invention). As may be seen in FIG. 6, thephenomenon of nonuniformity of flow rate of the first phase 61 in thelongitudinal direction z is greatly reduced with a device according tothe invention. Typically, the nonuniformities of the flow ratesdistributed by the orifices are reduced in such a way as to observevariations of less than 10% between the flow rates of the variousorifices.

Within the context of the invention, the evolution of the distancesbetween two successive positions z_(i), z_(i)+1, . . . can be assessedin the light of an evolution of actual, measured or simulated values, orof a so-called “fitted” or “smooth” evolution constructed from amathematical fitting of the actual evolution in the distances betweentwo successive positions z_(i), z_(i)+1, . . . .

Thus, the terms “increase” or “decrease” cover monotonic variations,like those illustrated in FIG. 5, or near-monotonic variations, whichmeans to say variations which locally, when considering the actual,measured or simulated values, exhibit a direction of variation thatdiffers from the overall direction of variation. For example, FIG. 7schematically indicates the result of a simulation that has led overallto an increase in the distances between two successive positions z_(i),z_(i)+1, . . . , but which, for certain points, exhibits a decrease inthe distance between one orifice and the next. A mathematical fitting ofthis evolution, indicated by the dashed curve (----), results in amonotonic increase of said distances. It should be noted that, as thecase may be, an orifice 34 _(i), may be situated in the same firstchannel 31 as the successive orifice 34 _(i+1), particularly in the caseof a mixer device 3 that has a single first channel 31, or may besituated in another first channel 31. In the case of a mixer device 3that has multiple first channels 31, a successive orifice 34 _(i+1) of afirst channel 31 is preferably situated in a different first channel 31from the orifice 34 _(i). The orifices 34 _(i), 34 _(i+1) are arrangedat positions z_(i), z_(i+1), . . . , without necessarily being arrangedat one and the same position in the lateral direction y.

The device 3 may comprise several first channels 31 arrangedsuccessively within the device 3, and/or several second channels 32, thefirst and/or the second channels 31, 32 being preferably parallel toeach other.

As a preference, the first channels 31 and the second channels 32 extendparallel to the plates 2. According to the embodiment illustrated inFIG. 3, the first channels 31 succeed one another in the lateraldirection y, and the second channels 32 succeed one another in thelongitudinal direction z.

It being emphasized that the channels 31 and 32 may have the same ordifferent shapes and quantities. The distances between the successivefirst channels 31 and the distances between the successive secondchannels 32 may also vary. As a preference, the distances between thechannels 32, measured in the direction of the longitudinal direction z,are adjusted according to the position of the orifices 34.

FIGS. 3 to 4 show examples of a mixer device 3 in the form of a bar,where openings 34 of cylindrical shape are drilled in the bottom ofseveral first channels 31.

In this embodiment, the mixer device 3 as a whole forms aparallelepiped, delimited in particular by a first surface 3 a intendedto be arranged facing one plate 2 of the exchanger, and a second surface3 b arranged facing another plate 2. The first and second surfaces 3 a,3 b preferably extend generally parallel to the plates 2. The mixerdevice 3 is preferably arranged in the passage 10 such that the firstand second surfaces 3 a, 3 b are in contact with the plates 2.

The channels 31, 32 advantageously take the form of recesses providedwithin the mixer device 3. They may or may not open onto the surfaces 3a and/or 3 b.

The orifices 34 are advantageously bores 34 made in the material of thedevice 3 and extending between the first channel 31 and the secondchannel 32, preferably in the vertical direction x. As a preference, theorifices 34 exhibit cylindrical symmetry.

It should be noted that the orifices 34 _(i), 34 _(i+1), . . . do notnecessarily have the same shape or the same dimensions. The number ofdifferent shapes, the dimensioning and the distribution of the orifices,in one and the same first channel 31 or between several first channels31, might vary according to the desired distribution of liquid-gasmixture, so as to achieve even finer adjustment of the flow rate offluid through the orifices 34. In particular, in the case of a firstchannel having an inlet 311, orifices of larger cross sections may bearranged upstream in the first channel 31, where the speed of the firstphase 61 is greater, and orifices of smaller inlet cross section may bearranged downstream in the first channel 31. The shape and thedimensions of the first and/or second channels 31, 32 may also varyalong the directions y and/or z, and from one channel 31, 32 to another.

Of course, the invention is not limited to the particular examplesdescribed and illustrated in the present application. Other alternativeforms or embodiments within the competence of a person skilled in theart may also be considered without departing from the scope of theinvention.

For example, the exchanger according to the invention is chieflydescribed for the case in which the passages 10, 20 extend in thelateral direction y, the first longitudinal channel 31 extending in theflow direction z, and the lateral channel 32 extending in the lateraldirection y orthogonal to the direction z. The reverse is alsoconceivable, for example a first longitudinal channel 31 extending inthe lateral direction y, and a lateral channel 32 extending in the flowdirection z. The directions y and z may also not be mutually orthogonal.

While the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, it is intendedto embrace all such alternatives, modifications, and variations as fallwithin the spirit and broad scope of the appended claims. The presentinvention may suitably comprise, consist or consist essentially of theelements disclosed and may be practiced in the absence of an element notdisclosed. Furthermore, if there is language referring to order, such asfirst and second, it should be understood in an exemplary sense and notin a limiting sense. For example, it can be recognized by those skilledin the art that certain steps can be combined into a single step.

The singular forms “a”, “an” and “the” include plural referents, unlessthe context clearly dictates otherwise.

“Comprising” in a claim is an open transitional term which means thesubsequently identified claim elements are a nonexclusive listing (i.e.,anything else may be additionally included and remain within the scopeof “comprising”). “Comprising” as used herein may be replaced by themore limited transitional terms “consisting essentially of” and“consisting of” unless otherwise indicated herein.

“Providing” in a claim is defined to mean furnishing, supplying, makingavailable, or preparing something. The step may be performed by anyactor in the absence of express language in the claim to the contrary.

Optional or optionally means that the subsequently described event orcircumstances may or may not occur. The description includes instanceswhere the event or circumstance occurs and instances where it does notoccur.

Ranges may be expressed herein as from about one particular value,and/or to about another particular value. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value and/or to the other particular value, along withall combinations within said range.

All references identified herein are each hereby incorporated byreference into this application in their entireties, as well as for thespecific information for which each is cited

1-16. (canceled)
 17. A heat exchanger comprising several plates arrangedparallel to one another and to a longitudinal direction so as to definea plurality of passages for channeling at least a first fluid which isto be brought into a heat-exchange relationship with at least a secondfluid, a mixer device being arranged in at least one passage andcomprising: at least one first channel for the flow of a first phase ofthe first fluid parallel to the longitudinal direction; at least onesecond channel for the flow of a second phase of the first fluid; and aplurality of orifices fluidically connecting the first channel to thesecond channel, said orifices occupying successive positions in thelongitudinal direction, wherein the distances between the successivepositions, measured parallel to the longitudinal direction, arevariable.
 18. The exchanger as claimed in claim 17, wherein thedistances between the successive positions vary monotonically ornear-monotonically in the longitudinal direction.
 19. The exchanger asclaimed in claim 17, wherein the exchanger exhibits, in the longitudinaldirection, an increase in the distances between two successivepositions.
 20. The exchanger as claimed in claim 17, wherein theexchanger exhibits, in the longitudinal direction, a decrease in thedistances between two successive positions.
 21. The exchanger as claimedin claim 17, wherein the exchanger is divided, in the longitudinaldirection, into at least a first portion and a second portion, the firstportion exhibiting, in the longitudinal direction, an increase in thedistances between two successive positions, and the second portionexhibiting, in the longitudinal direction, a decrease in the distancesbetween two successive positions.
 22. The exchanger as claimed in claim17, wherein the mixer device is configured for a separate introductionof the first phase and of the second phase into the at least one firstchannel and into the at least one second channel, respectively, thefirst channel comprising a first inlet designed to supply said firstchannel with the first phase of the first fluid and a second inlet,separate from the first inlet, designed to supply said at least onesecond channel with the second phase of the first fluid.
 23. Theexchanger as claimed in claim 17, wherein the first channel and thesecond channel are rectilinear in shape.
 24. The exchanger as claimed inclaim 17, wherein the the mixer device comprises several first channelsand several second channels, each first channel comprising at least oneorifice fluidically connecting said first channel to a given secondchannel.
 25. The exchanger as claimed in claim 17, wherein the mixerdevice comprises several first channels succeeding one another in alateral direction orthogonal to the longitudinal direction.
 26. Theexchanger as claimed in claim 17, wherein the second channel extends ina lateral direction orthogonal to the longitudinal direction.
 27. Amethod for distributing a two-phase liquid/gas mixture in an exchangeras claimed in claim 17, said method comprising the following steps: i)arranging a mixer device in at least one passage of the exchanger; ii)supplying said first channel of the mixer device with the first phase ofthe first fluid; iii) supplying said second channel of the mixer devicewith the second phase of the first fluid, which is distinct from thefirst phase; iv) establishing fluidic communication between the firstchannel and the second channel via the orifices so that a mixing betweenthe first phase and the second phase takes place within the mixerdevice; and v) distributing a mixture of the first phase and of thesecond phase at the outlet of the mixer device.
 28. A method foradjusting the position of the orifices of a mixer device incorporatedinto an exchanger as claimed in claim 17, said method comprising thefollowing steps: a) positioning the orifices in such a way that theirsuccessive positions are separated by predetermined distances; b)supplying the first channel with the first phase of the fluid such thatthe first phase of the first fluid flows in the longitudinal direction;c) determining the mass flow rates of the first phase flowing througheach orifice; and d) for each orifice, repositioning the next orifice sothat it is separated from the orifice by a modified distance equal tothe mean of the predetermined distances multiplied by a correctionfactor, said correction factor being determined on the basis of the massflow rate flowing through the orifice.
 29. The method as claimed inclaim 28, wherein the correction factor is a function of the ratiobetween the mass flow rate flowing through the orifice and the mass flowrate averaged over all the orifices.
 30. The method as claimed in claim29, said function is a polynomial function of the ratio, preferably anaffine function of the ratio.
 31. The method as claimed in claim 28,further comprising a step e) of defining the distances modified in stepd) as predetermined distances, steps c) to d) being reiterated at leastonce.
 32. The method as claimed in claim 31 wherein steps c) to d) arerepeated between 1 and 5 times.
 33. The method as claimed in claim 31wherein steps c) to d) are repeated at most twice.
 34. The method asclaimed in claim 28, wherein the mixer device comprises several firstchannels, the method comprising, prior to step a), at least one step ofselecting a subset of orifices which are arranged in one and the samefirst channel, steps a) to e) being applied to said sub set.